Ed Miliband will this Saturday become the first UK cabinet minister to hold an open conference call, potentially opening himself up to mass scrutiny over his climate change policies.

Thousands of callers are expected to dial in to quiz the climate change and energy secretary ahead of next week's UN summit in Copenhagen.

Miliband will experiment with a tactic pioneered by Barack Obama in the run-up to the 2008 US election, when the president used his teleconferences to brief supporters. The organisers, pressure group 38 degrees, say this should be more of a dialogue.

The conference call programme is mainly used by big banks to communicate company information with large numbers of shareholders. Callers will sign in on either Miliband's own website or at 38 degrees, and then they will receive a password and log in details on Friday.

Thousands are expected to join the call but most users will be held on mute until their question is chosen. The questions will be selected by a vote. 38 degrees are also setting up a twitter feed so people can respond in real time to Miliband's answers.

But as the online furore among climate sceptics over leaked emails between climate scientists continues, Miliband is likely to get many calls from people questioning whether global warming is happening at all.

But 38 Degrees say they are expecting no trouble: "Our members are a pretty constructive bunch."

A Downing St spokesperson described the event as similar to briefings made by Obama last year. The spokesperson: "[Miliband] feels that it's ordinary people and campaigners who have got us this far — and forced the pace of the [climate change] negotiations — so we now have a duty to keep them informed as best we can. This has been people-powered politics and we want to hold ourselves accountable to them."